1. Field of the Invention
The present invention relates to power line communications. Specifically, the present invention relates to adaptor devices configured to be attached to existing wall outlets, where the adaptor devices incorporate networking, power, and multimedia circuitry for communicating with various devices, systems, and networks.
2. Background of the Invention
There exist today many forms and types of networks, both wired and wireless, that allow for high speed data communication. The common thrust of all of these networks is to provide communication between devices, as well as access to the Internet. On the other hand, the common problem with many of these networks is that they have to be deployed, which can be very costly and time consuming just to set up the network infrastructure. In recent years there has been substantial interest in coming up with a way of communicating at high speeds and at high data rates over AC power lines. Power lines are advantageous because the network is already in place and is available to almost every home and business in the world.
Power lines and power transmission networks suffer from some problems, most notably noise and inconsistent impedance. Power line communication is not a new concept, and there have been various methods and technologies that have been developed to allow for reliable communication. One such method that can be used for broadband communication is OFDM (Orthogonal Frequency Division Multiplexing). This allows for the use of a large number of closely spaced carriers to transmit data across the line. This carrier multiplexing along with the use of data interleaving and FEC coding provide a robust and reliable communication method to overcome the inherent problems of a power line.
When looking at a common power transmission network, it can be broken up into three (3) main segments. From a standard power substation, there is commonly a “distribution” network of medium voltage power lines, configured in a loop and several miles in length, that feed out to an area of homes and businesses. Then, at various points on the loop there exist step down transformers that provide a series of 110-240 V “access” lines depending on the country to a small number of homes and/or businesses. At the end of each one of these lines there is typically a meter or meters present for each electricity customer served by that line. Then, on the other side of each meter there exists a typical “in-home” electricity distribution network inside a home or business.
It can be seen that all three of the network segments could possibly be used to transmit data across. However, it can be said that the “access” and “in-home” segments of this network are adjacent networks, with only an electricity meter in between. Also, it is very likely that the data transmitted on each of these segments will be for different purposes and have different destinations. For example, data transmitted on the access network segment could have multiple destinations or could be available to all end points, whereas data on an in-home network would likely be internal to that home or business. Thus, it is advantageous to logically separate these network segments to allow for separation and protection of data traveling on each segment. One possible method of accomplishing this is to allocate different frequency ranges or time segments for each segment. This allows for separation and also non-interference between segments.
A problem may arise, however, in this arena where there exists a legacy system in place, operating in a certain frequency range or within a predetermined time structure, and there is a desire to add communication on another network segment. In this case the legacy system may have to disable some of its carriers or reallocate time segments to allow for bandwidth allocated to the new system, thus diminishing its own bandwidth. However, the legacy system may not allow for this. It is also conceivable that the legacy system could be shifted up or shifted down in frequency or forced to change the behavior with regard to the timing of the communication to accommodate, but this would most likely require a change to the hardware and also would no longer allow it to communicate with other units of the same type. There is also the possibility of using blocking filters to isolate the network segments, but this would add extra expense and installation cost and may not be advantageous for many applications.
There exist today a number of communication networks that operate over a broad band and at high speeds. These networks may operate on different mediums and different frequency ranges, but they all must comply with a certain radiation limit as well as other limits that may be imposed based on other devices or networks operating in the same frequency range. Due to the broadband nature of these networks, it is likely that there will be areas of the frequency band that cannot be used due to other communication devices occupying these areas. A common example of this would be amateur radio bands that occupy certain frequencies throughout the RF radio spectrum. This may require notches to be put in place throughout a broadband communication system's operating frequency range. Another common requirement at the edges of this range is to have a steep roll off in transmitted power and be able to comply with a certain power spectral density limit beyond the edges of the operating frequency range. This often contributes to additional high-order filters or other means of spectral management being added to the design.
These high-order filter requirements can make the design of an analog front end very complicated, very large, and therefore very costly. In order to keep these issues in check, and to still satisfy the filtering requirements, it may be advantageous to increase the sampling frequency of the analog front end. This will often allow for simplifying of the filter designs as well as improved resolution on the received signal.
Power line communication (PLC) systems are well known in the art. See, for example, the book entitled “The Essential Guide to Home Networking Technologies” published in 2001 by Prentice-Hall, Inc., co-pending U.S. application Ser. No. 09/290,255, filed Apr. 12, 1999, the web site http://www.homeplug.org of the Home Plug Powerline Alliance and the article entitled “Home Plug Standard Brings Networking to the Home” in the December 2000 issue, Vol. 16, No. 12, of the Communication Systems Design magazine.
Power line communications for Internet access is a powerful technology that offers the consumer many real advantages over other forms (e.g., DSL, cable modems, etc.). These advantages include: power distribution networks to all homes and businesses are already in place, and PLC technology has been demonstrated to work at high data rates, as well as many other advantages. Power line communications allow making communication connections in a low cost manner between the power line distribution cables or wires, such as the pole-mounted cables or wires (any segment of the power line distribution network applies here including, but not limited to the LV (low voltage) and MV (medium voltage) networks and the home or business offices. Connecting to the power distribution network can be difficult and expensive requiring turning off network power during installation.
Power line communication systems apply modulated radio frequency carriers, e.g. carriers having frequencies in the range from about 2-80 MHz for access and from about 2 MHz to 50 MHz, for in home communications to power lines.
Electrical power distribution systems, commonly used in the United States, distribute the electrical power at 60 Hz from the source over cables, insulated or uninsulated. At the source, the voltage is high, e.g., over 200,000 volts and by means of transformers, the voltage is reduced by a transformer or transformers to a medium voltage, e.g., of the order of 20,000 volts, to be delivered to consumers by at least three cables or wires suspended from poles. At some of the poles, there are transformers which further reduce the voltage to low voltage of the order of 117 volts between a cable and a ground or neutral cable for the delivery of power to one or more customers or consumers. The power lines from the output of a pole transformer to the customers premises connect to a power consumption meter which in turn connects to the wiring in the customer's premises (e.g., home power wiring).
While the pole transformer and the power consumption meter cause comparatively little power loss at the low frequency at which the power is supplied, both the transformer and the meter can cause substantial radio frequency, communication signal power loss. Therefore, a parallel communication signal electrical path around at least the pole transformer has been provided to improve the communication signal power in the premises wiring. However, the prior art proposals for the parallel path have involved conductive (galvanic) connections both at the input and output of the pole transformer which requires skilled installers and in at least some cases, interruption of the power during installation of parallel path, by-pass equipment.
In today's world, a substantial number of household devices operate using some form of electricity. In one case, household devices operate using a battery power source that is integrated within the devices. These include laptop computers, stereo systems, electric shaving razors, etc. Typically, battery life of such devices is very limited, which prevents prolonged usage of the device and in some cases, such as laptop computers, causes possible loss of data, when batter runs out of power. Yet, other household devices cannot operate without being connected to a power outlet. Such device include kitchen devices (e.g., refrigerators, electric ranges, dishwashers, etc.), communications equipment (e.g., telephones, modems, routers, servers, etc.), multimedia devices (e.g., printers, facsimiles, televisions, DVD-players, VHS-players, desktop computers, etc.), and other devices that require sufficient continuous source of power to properly operate. Such devices are typically connected to a 110 Volt electrical outlet (or a 220 Volt outlet or other type voltage outlet depending on the country). Such electrical outlets are connected (e.g., hard-wired) to a number of electrical lines that are in turn hard-wired to electrical junction boxes in the house (or a building). The junction boxes are in turn connected to electrical micro-grids, which are part of larger grids connected to power stations that generate electricity, as illustrated in FIG. 1.
Typically, a household contains a specific number of electrical power outlets into which household devices can be plugged in. Such electrical power outlets as well as the junction box allow only a certain number of devices connected to the electrical system in the house, i.e., the electrical lines in the household are designed to accept a specific load. Each electrical line has a specific load limit that is determined by the amount of current that the line can supply. Exceeding electrical line's limit (i.e., connecting too many devices to the line) causes overload and a power outage on that particular electrical line. Thus, if too many devices are connected to the line, it may overload.
Further, a limited number of electrical outlets in the household prevents electrical connection of a group of devices located in one spot. For example, each of the following devices: a laptop computer, a printer located next to the computer, a modem, a router, a server, a laptop speaker system, and other multi-media devices, may require a separate electrical outlet. A power strip device that plugs into the electrical outlet may accommodate electrical needs of all of these devices by providing multiple sockets on a single power strip plate. The power strip then connects to the available electrical outlet with a single plug. However, the power strip device adds to the clutter with the wires coming from the connecting devices, consumes an electrical outlet and prevents other devices from connecting to the power outlet. The power strip device may also immobilize mobile units having wireless communication capabilities.
Currently available electrical outlet adaptors include vapor dispensing devices. The vapor dispensing adaptor attaches to an electrical outlet and dispenses aroma vapors. In some cases, the vapor dispensing adaptor devices are plugged into the outlet, thereby consuming one or all available electrical sockets. In other cases, the vapor dispensing adaptors are plugged into the outlet but retain the availability of the sockets. However, they do not provide for connection to multimedia, networking, and communication devices.
Additionally, some conventional outlet adaptor devices that can be plugged into an existing outlet are extremely bulky. When plugged in, these adaptor devices substantially protrude away from the wall, consume a lot of space, create an obstacle when placing objects in their vicinity, and do not preserve outlet space.
Thus, there is a need for a power outlet adaptor device that is capable of preserving electrical outlet availability for connection of devices, providing multimedia, networking, and other communication capabilities to devices, and retaining an aesthetic appeal of an electrical outlet. There is also a need for an outlet adaptor device that has multimedia, networking, and communication capabilities as well as resembles a standard electrical wall outlet without substantially protruding away from the wall, and thus, retaining its aesthetic appeal.